Ease of analysis through unification: One gas chromatographic method for the chemical profiling of essential oils

The rising interest in essential oils (EOs) for their therapeutic, antibacterial, and antifungal properties has led to an increasing demand for high-quality products in both medicinal and industrial sectors. To meet these stringent quality requirements, robust, precise, and efficient analytical methods are essential. Gas chromatography (GC) remains the gold standard for EO analysis due to its sensitivity and resolution. Although numerous methods are available -primarily targeting similar analytes in varying combinations standardization remains a challenge, with protocols differing across ISO guidelines and international pharmacopoeias. In this study, Design of Experiments (DoE) was employed to optimize and harmonize existing GC methods, focusing on sample preparation and chromatographic parameters. A polar GC column (60 m length, 0.25 mm inner diameter, 0.25 µm film thickness) was selected for its ability to effectively separate 87 terpenes, sesquiterpenes, and related compounds commonly found in EOs. The optimized temperature gradient enabled complete separation within a 75-minute runtime, outperforming or matching existing methods in terms of resolution and reproducibility. Streamlined sample preparation protocols led to reduced solvent consumption and minimized sample requirements across all tested EOs. As a proof of concept, the final method was applied to 12 different essential oils, demonstrating comparable analytical performance and confirming its broad applicability and efficiency.